Hands-on Projects for the Linux Graphics Subsystem

PCI Experiments (part II)

In the current section we continue with the lspci Unix command and see some and this time we use
the -v (verbose) option:

sudo lspci -v

Notice that root privilege (sudo) is required for lspci in order to reveal the values in
the 'Capabilities' field. The output in our system in the Display and VGA part that is discussed
here was:

As we see in the previous image lspci indicates at the Kernel modules field the Intel i915
driver. This is a misconception since the driver currently used by our system is vesa. In the following figure we see that xorg.conf, the configuration file for the X Server, uses the vesa driver:

Also looking at the Xorg.0.log file, the X Server log file for display 0, we find in the
driver list loaded by the X Server the vesa driver (vesa_drv.so):

more /var/log/Xorg.0.log | grep Loading

The output is the following:

The following text tries to present an explanation for the i915 appearance in the lspci output
starting with depmod.

We notice that the i915 module has a vendor id 0x8086 and also a device id 0x3582.

As we recall from section 4.2.4
0x3582 represents the device id of the video card and 0x8086
represents the vendor id of Intel. The next figure shows the output of lspci -x as we saw it
in section 4.2.4:

Since for Linux lspci searches modules.pcimap and in our case it found the same vendor id and
device id it included in the output the module i915, which is the one that appears in the
modules.pcimap.